Gas flow measurement system and method of operation

ABSTRACT

A gas flow monitoring system is disclosed that includes a plurality of first gas flow sensors. A primary probe transmitter is connected to the plurality of first gas flow sensors is configured to process data received from the plurality of first gas flow sensors to generate first gas flow data. A plurality of second gas flow sensors are connected to an ancillary probe transmitter and to the primary probe transmitter, where the ancillary probe transmitter are configured to process data received from the plurality of second gas flow sensors to generate second gas flow data. The primary probe transmitter further comprises a building automation system interface, and is configured to receive the second gas flow data from the ancillary probe transmitter and to transmit the first gas flow data and the second gas flow data to a building automation system.

RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No. 61/798,528, filed Mar. 15, 2013, entitled “GAS FLOW MEASUREMENT SYSTEM AND METHOD OF OPERATION,” which is hereby incorporated by reference for all purposes as if set forth herein in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to gas flow measurement, and more specifically to a gas flow measurement system and method of operation that allows for peer to peer communications between flow measurement devices.

BACKGROUND OF THE INVENTION

Currently available gas flow measurement devices generate analog signals that are sent to an externally wired control panel. The externally wired control panel interprets analog values and calculates gas flow measurment values. The externally wired control panel communicates the calculated flow information to a building autotmation system digitally or through analog signal. If more than one flow measurement device is required to provide adequate representation of the flow at any given measurement location within the system, these devices communicate with a separate control panel. The control panel utilizes code to calculate a flow that is an average of all the sensors circuits at that location. Currently, the typical system utilizes one to four measurement devices per flow measurement location. Each device may have up to four sensor circuits, with a maximum of sixteen sensor circuits for a give location. These sixteen sensor points, located on up to four flow measurement devices, communicate to a separate remote control panel that calculate an average flow at the measurement devices over long lines, where the sensor signal data can be exposed to noise or other data corruption. The building automation system communicates with the separate control panel, and does not communicate with flow measurement devices individually.

SUMMARY OF THE INVENTION

A gas flow monitoring system is disclosed that includes a plurality of first gas flow sensors. A primary probe transmitter is connected to the plurality of first gas flow sensors and is configured to process data received from the plurality of first gas flow sensors to generate first gas flow data. A plurality of second gas flow sensors are connected to an ancillary probe transmitter and to the primary probe transmitter, where the ancillary probe transmitter is configured to process data received from the plurality of second gas flow sensors to generate second gas flow data. The primary probe transmitter further comprises a building automation system interface, and is configured to receive the flow data from all ancillary probe transmitters connected in a digital communication network and transmits the first gas flow data and the second gas flow data from all ancillary probe transmitters to a building automation system.

Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and in which:

FIG. 1 is a diagram of a system for gas flow measurement in accordance with an exemplary embodiment of the present disclosure;

FIG. 2 is a diagram of a system for gas flow measurement in accordance with an exemplary embodiment of the present disclosure;

FIG. 3 is a diagram of a transmitter enclosure in accordance with an exemplary embodiment of the present disclosure;

FIG. 4 is a diagram of a probe assembly in accordance with an exemplary embodiment of the present disclosure;

FIG. 5 is a diagram of a probe assembly in accordance with an exemplary embodiment of the present disclosure;

FIG. 6 is a diagram of a sensor hood assembly in accordance with an exemplary embodiment of the present disclosure;

FIG. 7 is a diagram of a thermistor in accordance with an exemplary embodiment of the present disclosure;

FIG. 8 is a diagram of a control interface in accordance with an exemplary embodiment of the present disclosure; and

FIG. 9 is a diagram of a system for managing an air handling system in accordance with an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals. The drawing figures might not be to scale and certain components can be shown in generalized or schematic form and identified by commercial designations in the interest of clarity and conciseness.

FIG. 1 is a diagram of a system 100 for gas flow measurement in accordance with an exemplary embodiment of the present disclosure. System 100 includes primary probe transmitter 106 and ancillary probe transmitters 108A through 108E. Primary probe transmitter 106 is coupled to air measurement probe assembly 102 and includes data processing and communications systems that can transmit and receive signals from air measurement probe assembly 102, which can include one or more sensors for measuring air flow and volume using differential pressure, thermal dispersion, hot wire anemometer, vortex shedding, heated mass or other suitable technologies, and can perform local processing of the signals to generate air flow data, air volume data or other suitable data. Primary probe transmitter 106 can also interface with a local display device on controller 118, can perform analysis of individual sensor signals, such as to detect sensors that are misoperating, that have been installed in a location that is shielded from air flow or subject to gusts, or that should otherwise be omitted from air flow readings. In one exemplary embodiment, primary probe transmitter 106 and air measurement probe assembly 102 can be similar to the systems and components described in U.S. Pat. No. 7,860,667, issued Dec. 28, 2010, entitled “Gas Measurement System,” which is hereby incorporated by reference for all purposes as if set forth in its entirety.

As used herein, “hardware” can include a combination of discrete components, an integrated circuit, an application-specific integrated circuit, a field programmable gate array, or other suitable hardware. As used herein, “software” can include one or more objects, agents, threads, lines code, subroutines, separate software applications, two or more lines of code or other suitable software structures operating in two or more software applications, on one or more processors (where a processor includes a microcomputer or other suitable controller, memory devices, input-output devices, displays, data input devices such as keyboards, peripherals such as printers and speakers, associated drivers, control cards, power sources, network devices, docking station devices, or other suitable devices operating under control of software systems in conjunction with the processor or other devices), or other suitable software structures. In one exemplary embodiment, software can include one or more lines of code or other suitable software structures operating in a general purpose software application, such as an operating system, and one or more lines of code or other suitable software structures operating in a specific purpose software application. As used herein, the term “couple” and its cognate terms, such as “couples” and “coupled,” can include a physical connection (such as a copper conductor), a virtual connection (such as through randomly assigned memory locations of a data memory device), a logical connection (such as through logical gates of a semiconducting device), other suitable connections, or a table combination of such connections.

Primary probe transmitter 106 includes network connections 110 and 112, and is coupled to power supply 114 through power strip 116. Primary probe transmitter 106 is coupled to ancillary probe transmitters 108A through 108E over wire line serial connection 120. Each of ancillary probe transmitters 108A through 108E includes suitable processing systems and components to provide signals to and receive signals from sensors on air measurement probe assemblies 104A through 104E, respectively, and to process the signals to generate air flow data, air volume data and other suitable data. Ancillary probe transmitters 108A through 108E can also generate air flow data that includes readings attributable to individual sensors, and can process the air flow data for transmission to each other and to primary probe transmitter 106. In one exemplary embodiment, primary probe transmitter 106 can receive the air flow data from each of ancillary probe transmitters 108A through 108E and can transmit the air flow data in conjunction with air flow data generated by primary probe transmitter 106 to a building automation system or other suitable systems, such as by packetizing the data, by transmitting the data at predetermined times, by transmitting the data in response to prompts, or in other suitable manners. In another exemplary embodiment, primary probe transmitter 106 and ancillary probe transmitters 108A through 108E can communicate in a peer to peer manner with each other and with external systems, can communicate using an ad hoc wireless network, or can use other suitable communications media, system and protocols to allow existing wireless or wire line network communications to be used, to distribute processing and control of sensors to facilitate providing service to the sensors, and for other suitable purposes. Unlike prior art systems that required each measurement station to be connected to a remote processor dedicated wire line connections and which only provided limited data to a building automation system through the remote processor, system 100 provides significantly improved flexibility and data availability at significantly lower cost.

In one exemplary embodiment, system 100 can utilize thermal dispersion technology to measure and report air velocity or volume. Primary probe transmitter 106 can be installed at one location in the air measurement station serial communication network and can include an expansion header to interface with a building automation system network. Primary probe transmitter 106 can include a plastic hinged enclosure that houses the associated electronic systems, and which can include suitable data communication circuitry, such as by using the MODBUS serial communications protocol or other suitable data communications systems or processes. Controller 118 can include a graphical LCD and touch screen interface and can be wired into the MODBUS network or other suitable communications media to allow an operator to perform system adjustment at or near primary probe transmitter 106 and ancillary probe transmitters 108A through 108E, to receive a visual indication of airflow and temperature, and to perform other suitable functions. Ancillary probe transmitters 108A through 108E can be installed in multiple openings such as the outside air, return air, and exhaust air of an air handling unit. Primary probe transmitter 106 can include a 16×2 LCD display with a five button overlay installed on the outside of the plastic box hinged cover or other suitable display and control systems.

FIG. 2 is a diagram of a system 200 for gas flow measurement in accordance with an exemplary embodiment of the present disclosure. System 200 includes primary probe transmitter 206 and associated probe assembly 202, and ancillary probe transmitters 208A through 208E and associated probe assemblies 204A through 204E. Ancillary probe transmitters 208A through 208E communicate with each other and primary probe transmitter 206 over wireless network 212, which can be an IEEE 801.x wireless network or other suitable wireless networks.

FIG. 3 is a diagram of a transmitter enclosure 300 in accordance with an exemplary embodiment of the present disclosure. Transmitter enclosure 300 includes base 304 and hinged cover 302, which enclose circuit board 306. Circuit board 306 is secured to transmitter enclosure 300 using bolts 308. Circuit board 306 can be used to provide primary probe transmitter 106, ancillary probe transmitter 108 or other suitable circuits and systems to allow signals to be provided to and receive from sensors locally, without requiring long and dedicated communication lines with the sensors o be run through a noisy environment to a remote processor.

FIG. 4 is a diagram of a probe assembly 400 in accordance with an exemplary embodiment of the present disclosure. Probe assembly 400 includes support bar 402, which can be formed of aluminum or other suitable materials and which can include one or more sensors. Supports 404 and 406 can be used to secure support bar 402 to a duct, an air handling equipment enclosure, or other suit able locations. Transmitter enclosure 300 couples to support 404 and can receive wires from sensors on support bar 402, such as through the center of support bar 402 or in other suitable manners. In one exemplary embodiment, support bar 402 can include one or more energy harvesting devices, such as a micro turbine, to allow energy for operating primary probe transmitter 106, ancillary probe transmitter 108 or other suitable systems or components to be generated locally from the air flow that is being measured, so to allow components of the air flow monitoring system that are capable of wireless communications to be installed without the need for routing power cables to each monitoring station.

FIG. 5 is a diagram of a probe assembly 400 in accordance with an exemplary embodiment of the present disclosure. Probe assembly 400 includes sensor assemblies 502 through 508, which are located at one or more predetermined. locations along support bar 402. In operation, air flow in either direction shown by arrow 510 causes sensors 502 through 508 to generate signals that can be processed to generate air flow data.

FIG. 6 is a diagram of a sensor hood assembly 600 in accordance with an exemplary embodiment of the present disclosure. Sensor hood assembly 600 includes sensor hood 602, which can be formed from acrylonitrile butadiene styrene (ABS) or other suitable materials, and includes thermistor 604, which can be used for self-heating, ambient temperature measurement or other suitable purposes. Thermistor 604 can be secured directly to sensor hood 602 with epoxy or in other suitable manners. The thermistor leads can be attached directly to wire by a crimping tool or in other suitable manners, and heat shrink tubing can be used to insulate and protect the connection. The thermistor wires can run through an aluminum extrusion of sup port bar 402 to primary probe transmitter 106, ancillary probe transmitter 108 or other suitable circuits or systems that are mounted on the end of the air measurement probe assembly inside the plastic enclosure with hinged lid.

FIG. 7 is a diagram of a thermistor 700 in accordance with an exemplary embodiment of the present disclosure. Thermistor 700 includes two solid nickel conductors 702 with heavy polyurethane nylon insulation and sensor element 704.

FIG. 8 is a diagram of a control it 800 in accordance with an exemplary embodiment of the present disclosure. Control interface 800 can be implemented in hardware or a suitable combination of hardware aid software, and can be one or more software systems operating on a processor. In one exemplary embodiment, control interface 800 can be generated at a touch screen controller that operates in conjunction with one or more of primary probe transmitter 106 and ancillary probe transmitters 108 or in other suitable manners.

Control interface 800 includes gas flow measurement controller 802, which can be implemented in conjunction with a primary probe transmitter, an ancillary probe transmitter, a touch screen controller or other suitable systems. Gas flow measurement controller 802 includes device reset system 804, field balance system 806, error indication system 808, test system 810, velocity and temperature display system 812, airflow velocity adjustment system 814, zero cutoff adjust system 816 and gust filtering system 818. Gas flow measurement controller transmits signals to and receives signals from a plurality of sensors, such as a plurality of thermistors for self-heating, a plurality of thermistors for ambient temperature measurement, or other suitable sensors, and processes the data to generate air flow data, such as velocity data or volume data.

Device reset system 804 generates a user control and processes user-entered commands to reset one or more devices. In one exemplary embodiment, device reset system 804 can be implemented using one or more objects that have associated graphical, data and control attributes. Device reset system 804 can interface with one or more devices associated with a primary probe controller, an ancillary probe controller or other suitable systems, such as to reset the primary probe controller or ancillary probe controller, to reset one or more air measurement device settings, or to perform other suitable functions.

Field balance system 806 generates a user control and processes user-entered commands to balance one or more networked air measurement devices. In one exemplary embodiment, field balance system 806 can be implemented using one or more objects that have associated graphical, data and control attributes. Field balance system 806 can interface with one or more networked air measurement devices associated with a primary probe controller, an ancillary probe controller or other suitable systems, such as to allow personnel to balance networked air measurement devices in the vicinity of field balance system 606, or to perform other suitable functions.

Error indication system 808 generates a user control and processes user-entered commands to display error data, such as device or sensor error data. In one exemplary embodiment, error indication system 808 can be implemented using one or more objects that have associated graphical, data and control attributes. Error indication system 808 can interface with one or more devices associated with a primary probe controller, an ancillary probe controller or other suitable systems, such as to receive error signals and to translate the error signals to user readable displays, or to perform other suitable functions.

Test system 810 generates a user control and processes user-entered commands to test one or more devices. In one exemplary embodiment, test system 810 can be implemented using one or more objects that have associated graphical, data and control attributes. Test system 810 can interface with one or more devices associated with a primary probe controller, an ancillary probe controller or other suitable systems, such as to generate a sequence of data signals or test signals to determine whether response signals generated by the devices indicate that the devices are functioning properly, to perform other suitable functions.

Velocity and temperature play system 812 generates a user control and processes user-entered commands to display velocity and temperature data for air measurement devices. In one exemplary embodiment, velocity and temperature display 812 can be implemented using one or more objects that have associated graphical, data and control attributes. Velocity and temperature display 812 can generate velocity and temperature data for individual sensors or sets of sensors, such as to allow personnel to compare independent velocity and temperature measurements with velocity and temperature measures for one or more air measurement devices in the vicinity of velocity and temperature system 812, or to perform other suitable functions.

Airflow velocity adjustment system 814 generates a user control and processes user-entered commands to adjust gain and offset of airflow velocity measurements. In one exemplary embodiment, airflow velocity adjustment system 814 can be implemented using one or more objects that have associated graphical, data and control attributes. Airflow velocity adjustment system 814 can interface with gain and offset controls for one or more air measurement devices associated with a primary probe controller, an ancillary probe controller or other suitable systems, such as to allow personnel to adjust gain and offset for air measurement devices in the vicinity of airflow velocity adjustment system 814, to perform other suitable functions.

Zero cutoff adjust system 816 generates a user control and processes user-entered commands to adjust or establish zero cutoff value for a selected airflow station. In one exemplary embodiment, zero cutoff adjust system 816 can be implemented using one or more objects that have associated graphical, data and control attributes. Zero cutoff adjust system 816 can interface with one or more air measurement devices associated with a primary probe controller, an ancillary probe controller or other suitable systems, such as to allow personnel to establish a zero cutoff value, or to perform other suitable functions.

Gust filtering system 818 generates a user control and processes user-entered commands to perform gust filtering and velocity measurement averaging for a plurality of sensor signals. In one exemplary embodiment, gust filtering system 818 can be implemented using one or more objects that have associated graphical, data and control attributes. Gust filtering system 818 can interface with one or more air measurement devices associated with a primary probe controller, an ancillary probe controller or other suitable systems, such as to perform gust filtering or velocity measurement averaging, or to perform other suitable functions.

Building automation system interface 820 receives data from gas flow measurement controller 802 and interfaces with a building automation system to receive and transmit data. In one exemplary embodiment, a building automation system can be configured to access the additional data that is available from gas flow measurement controller 802 to provide better data for the purposes of determining the state of the air handling system, to identify misoperating equipment, to control air handling equipment to optimize performance, or for other suitable purposes.

FIG. 9 is a diagram of a system 900 for managing an air handling system in accordance with an exemplary embodiment of the present disclosure. System 900 includes building automation system 902, which can receive data from a plurality of different systems over network 914, such as lighting data, power consumption data, alarm data and heating, ventilating and air conditioning (HVAC) data. Network 914 can be a wire line network such as an Ethernet network, an optical network, a wireless network, other suitable networks or a suitable combination of such networks.

Primary probe transmitters 904 and 908 receive data from sensors and generate HVAC data that is transmitted to building automation system 902 over network 914. Primary probe transmitter 904 receives data from sensors at ancillary probe transmitter 906, HVAC data from ancillary probe transmitter 906 or other suitable data over serial or parallel communication link 918 and processes the data for transmission over network 914, such as by compiling the data into a predetermined data packet format, by generating the data in response to a query from building automation system 902 or in other suitable manners. Primary probe transmitter 908 receives data from sensors at ancillary probe transmitter 910, HVAC data from ancillary probe transmitter 910 or other suitable data over wireless network 916 and processes the data for transmission over network 914, such as by compiling the data into predetermined data packet format, by generating the data in response to a query from building automation system 902 or in other suitable manners. Likewise, where suitable, ancillary probe transmitter 912 can communicate directly with building automation system 902 or other suitable systems, such as personal data device. In this manner, building automation system 902 can receive data from individual air monitoring stations or even individual sensors, if desired, and data processing of sensor data for HVAC data can be distributed to local probe transmitters, can also or alternatively be performed centrally at building automation system 902 or other suitable processes can also or alternatively be implemented.

In one exemplary embodiment, system 100 and the other systems and components described herein can facilitate processing and control of sensors to generate air flow data. In this exemplary embodiment, a method for monitoring gas flow can be used that includes receiving a data signal from each of a plurality of first gas flow sensors at primary probe transmitter 106, which processes the plurality of first gas flow sensor data signals to generate first gas flow data. A data signal can be received from each of a plurality of second gas flow sensors at an ancillary probe transmitter 108, which can process the plurality of second gas flow sensors data signals to generate second gas flow data. Likewise, additional ancillary probe transmitters and sensors can be used where suitable.

The second gas flow data is transmitted to primary probe transmitter 106 over a first communications media, such as serial communication media, a wireless network or other suitable media and primary probe transmitter 106 assembles the first gas flow data and the second gas flow data for transmission over a network, such as a wire line network, a wireless network or other suitable data networks. Primary probe transmitter 106 then transmits the first gas flow data and the second gas flow data to a building automation system.

In one exemplary embodiment, data signals can be received from one or more thermistors for self-heating ambient temperature measurement. Gas flow data can be generated from data received from each of the first gas flow sensors, such as velocity data, volume data, temperature data or other suitable data. The data from the gas flow sensors can be processed to determine whether individual sensor signals should be omitted from gas flow data generated by primary probe transmitter 106, ancillary probe transmitter 108 or other suitable systems, such in response to testing of the gas flow sensors for operability.

It should be emphasized that the above-described embodiments are merely examples of possible implementations. Many variations and modifications may be made to the above-described embodiments without departing from the principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims. 

1-20. (canceled)
 21. A gas flow monitoring system comprising: a plurality of first gas flow sensors dispose at predetermined intervals along a support bar to form a probe; and a primary probe transmitter coupled to the plurality of first gas flow sensors and the support bar and configured to process data received from the plurality of first gas flow sensors to generate first gas flow data.
 22. The gas flow monitoring system of claim 21 wherein the primary probe transmitter is enclosed within a duct.
 23. The gas flow monitoring system of claim 21 further comprising a plurality of second gas flow sensors disposed on a first structure at a first location within a duct and wherein the support bar is disposed at a second location that is different from the first location.
 24. The gas flow monitoring system of claim 21 further comprising an ancillary probe transmitter coupled to a plurality of second gas flow sensors at a first location within a duct and to the primary probe transmitter, the ancillary probe transmitter configured to process data received from the plurality of second gas flow sensors to generate second gas flow data, and wherein the support bar is disposed at a second location that is different from the first location.
 25. The gas flow monitoring system of claim 21 wherein the primary probe transmitter further comprises a building automation system interface and configured to receive second gas flow data from an ancillary probe transmitter, to process the first gas flow data and the second gas flow data to generate first processed data, and to transmit the first gas flow data, the second gas flow data and the first processed data to a building automation system.
 26. The gas flow monitoring system of claim 21 wherein the primary probe transmitter is coupled to an ancillary probe transmitter over a wireless network and the primary probe transmitter is coupled to a building automation system over a wire line network.
 27. The gas flow monitoring system of claim 21 wherein the plurality of first gas flow sensors comprise a first plurality of thermistors for self-heating and a first plurality of thermistors for ambient temperature measurement.
 28. The gas flow monitoring system of claim 27 wherein the primary probe transmitter further comprises an error indication system configured to receive a signal from each of the plurality of thermistors for self-heating and to generate a user-readable indication as a function of each of the error signals.
 29. The gas flow monitoring system of claim 21 wherein the first gas flow data comprises gas flow data for each of the plurality of first gas flow sensors.
 30. The gas flow monitoring system of claim 21 wherein the first gas flow data comprises one or more of velocity data and volume data.
 31. The gas flow monitoring system of claim 21 further comprising a touch screen controller coupled to the primary probe transmitter and configured to generate one or more user prompts and to receive user-entered selections in response to the user prompts.
 32. The gas flow monitoring system of claim 21 further comprising: a first housing containing the primary probe transmitter, the first housing configured to be attached to an air flow component at a first location; and a first sensor support coupled to the first housing and the air flow component at the first location, wherein the plurality of first gas flow sensors are disposed on the first sensor support.
 33. The gas flow monitoring system of claim 32 further comprising: a second housing containing an ancillary probe transmitter, the second housing configured to be attached to the air flow component at a second location; and a second sensor support coupled to the second housing and the air flow component at the second location, wherein the plurality of second gas flow sensors are disposed on the second sensor support.
 34. A method for monitoring gas flow comprising: receiving a data signal from each of a plurality of first gas flow sensors at a primary probe transmitter at a first location within a duct; processing the plurality of first gas flow sensor data signals to generate first gas flow data; receiving a data signal from each of a plurality of second gas flow sensors at an ancillary probe transmitter; processing the plurality of second gas flow sensors data signals to generate second gas flow data; transmitting the second gas flow data to the primary probe transmitter over a first communications media; assembling the first gas flow data and the second gas flow data for transmission over a network at the primary probe transmitter; and transmitting the first gas flow data and the second gas flow data from the primary probe transmitter to a building automation system.
 35. The method of claim 34 wherein receiving the data signal from each of the plurality of second gas flow sensors at the ancillary probe transmitter comprises receiving the data signal from each of the plurality of second gas flow sensors at the ancillary probe transmitter from a second location within the duct.
 36. The method of claim 35 wherein processing the plurality of first gas flow sensor data signals to generate the first gas flow data comprises generating first gas flow data for each of the plurality of first gas flow sensors.
 37. The method of claim 35 wherein processing the plurality of first gas flow sensor data signals to generate the first gas flow data comprises generating one or more of velocity data and volume data.
 38. The method of claim 35 wherein processing the plurality of first gas flow sensor data signals to generate the first gas flow data comprises generating one or more of velocity data and volume data for each of the plurality of first gas flow sensors.
 39. The method of claim 35 further comprising determining whether one or more of the plurality of first gas flow sensor data signals should be omitted from the first gas flow data at the primary probe transmitter.
 40. The method of claim 35 further comprising testing each of the plurality of first gas flow sensors for operability with the primary probe transmitter as a function of a location of each of the plurality of first gas flow sensors within the duct. 